Creep in Cellulose Acetate Filaments

The elongation of a series of single cellulose acetate filaments stressed for a period of 29 days with a constant load has been measured at relative humidity values ranging from 0 to 100% in nominal steps of 10%. The creep (elongation under constant stress) continues indefinitely but at a rapidly decreasing rate in all the fibres. The rate of creep is found to decrease with the total time of stressing with certain superimposed discontinuities which scem to indicate transitions frorn one manner of shear slip to another. The amount of creep at the end of any arbitrarily fixed time increases slowly between 0 and about 60% relative humidity, but above 60% the increase is very rapid. Rupture seems to be governed by a limiting elongation (maximum strain).